The elastic properties of many vertebrate tissues are due largely to elastic fibers, made up of two morphologically and biochemically distinct components: (1) elastin responsible for elasticity, (2) the multi-protein microfibrillar component, whose function is not well defined, but which appears to have some role in organizing the fiber or controlling fiber formation. Because microfibrillar proteins are rather insoluble and intractable to biochemical analysis, present understanding of them is limited, warranting new approaches. The investigators have begun a collaborative molecular and cellular biology attack directed at determining: (1) the properties of these proteins, (2) their relationship to elastin, (3) their function, and (4) the regulation of their expression. To achieve these goals, they now propose to (1) complete the isolation and characterization of the cDNAs and genes encoding the 31 (MAGP) , 70, and 340 (fibrillin) kDa microfibrillar proteins, (2) determine the functional characteristics of the promoters of these genes, (3) determine when and in which bovine tissues the microfibrillar proteins are expressed, (4) determine the nature of any interactions among the microfibrillar proteins and with tropoelastin, (5) elucidate mechanisms involved in elastic fiber assembly. The studies will employ a wide variety of molecular biology (cloning and sequencing, transfection, recombinant synthesis of proteins), cell biology (cell culture, in vitro fiber assembly), immunologic (production of monospecific antibody, immunohistochemical and EM analyses), and protein (peptide synthesis and sequencing, protein-protein interactions) methods, all of which are currently on-going in the investigators ' laboratories. Elastic fibers are critical components of the extracellular matrix of many vital tissues, including major blood vessels, the lung, and the dermis. Derangements in the fibers probably play a decisive role in the pathology of a variety of heritable (i. e. Marfan's Syndrome) and acquired (i.e. emphysema) diseases. Definition of the molecular structure of the fibers and the mechanisms involved in their synthesis and assembly are requisite to understanding these derangements and to devising cures.